Trimmer lawn mowing device

ABSTRACT

A lawn trimming device attachable or attached to the power take off end of a line trimmer primary unit to be powered by the line trimmer. The device includes a hood with a downwardly facing opening to allow the opening to be placed parallel to the ground, the hood defining a cutting cavity. A means for coupling the hood to the line trimmer primary unit is provided and a shaft is included. A cutting means rotatably mounted relative to the hood from the shaft is provided and wherein the shaft is engageable to the line trimmer primary unit to derive rotational power from the line trimmer primary unit. The cutting means is positioned within the cutting cavity of the hood adjacent the opening. A hovering fan is also preferably included within the hood.

FIELD OF INVENTION

The present invention relates to a line trimmer lawn mowing device.

BACKGROUND

Line trimmers of the kind which are often used for trimming the edges oflawn or for trimming weed or indeed for trimming grass such as is oftenfound on the sides of roads or-highways include a motor (usually aninternal combustion motor) which is engaged to the end of a shaft. Themotor will drive a shaft which at the other end has attached the cuttingelement. A cutting element may for example be a fixed blade oralternatively be a nylon string which is rotationally driven via theshaft by the motor. The cutting elements can be exposed to the grass orweed to cut the grass or weed at the desired height. The unit willnormally include a handle and rpm controller to control the rpm's of themotor. For heavier units the line trimmer may also include a supportharness which can be slung about the body of a user to provide supportby the user to the weight of the unit. Whilst some versions of a linetrimmer will provide a guard presenting protection to the cuttingelements in a direction of the body of the user, such a guard merelyserves the purpose of providing protection, and then only in ondirection or arc of directions.

A standard line trimmer however has difficulty in being used for cuttinglawn to a desired level. Since the cutting elements can be held at avarying height above the ground careful control is needed to beexercised by the user to achieve a cut of grass at a consistent heightacross the entire area of the lawn. This can be difficult to achieve andif the line trimmer is held at the wrong angle, can result in gauging ofthe lawn thereby creating an uneven look to the height of the cut grass.It is appreciated that lawn mowers can achieve a consistent height inthe cutting of grass thereby. However lawn mowers are relatively largetools and its certain applications particularly in residential or innercity locations where the amount of grass that is to be cut is relativelyminimal, it may not be desirable or practical to use a lawn mower forcutting the grass.

Accordingly it is an object of the present invention to provide a linetrimmer lawn trimmer attachment unit which addresses the abovementioneddisadvantages or which will at least provide the public with a usefulchoice.

BRIEF DESCRIPTION OF THE INVENTION

Accordingly in a first aspect the present invention consists in a lawntrimmer component for attachment to a hand held prime mover of a kindwhich includes a motor (electric or internal combustion) with which anelongate drive shaft is connected to be rotationally driven by saidmotor said shaft captured substantially within a protective sleeverigidly connected (directly or indirectly) to said motor, said shaftpresented at an end of said sleeve away from said motor for coupling tosaid lawn trimmer component, said lawn trimmer component comprising:

-   -   (a) a rotary shaft to derive rotational power via said elongate        drive shaft from said motor for rotating said rotary shaft about        an axis of rotation    -   (b) a coupling device engaged to said rotary shaft and engagable        with said end of said sleeve of said prime mover    -   (c) a cutting means engaged to and radially disposed from said        rotary shaft to rotate about said axis of rotation    -   (d) a hood defining a cutting chamber extensive over said        cutting means yet exposing said cutting means to an opening of        said hood which, in use, is to be positioned juxtaposed the        ground over which said lawn trimmer component is, by control of        said prime mover, moved by a user, wherein said hood is mounted        stationary to said rotary shaft save for the relative rotation        of said rotary shaft with said hood about said axis of rotation.

Preferably said opening of said hood is a planar opening.

Preferably said cutting means extends from said rotary shaft to presenta cutting edge thereof substantially parallel to the plane of saidopening.

Preferably said opening of said hood is at least coextensive with thecutting profile generated by said cutting means when rotated about saidaxis of rotation.

Preferably said opening of said hood is at least coextensive with thecircular perimeter traced by said cutting edge when rotated about saidaxis of rotation.

Preferably said rotary shaft is engaged to and to be supported from saidhood by a cylindrical bearing.

Preferably said rotary shaft includes a cutting means mount with whichsaid cutting means is affixed and a stub axle extending therefromcoaxial with said axis of rotation, said stub axle supporting said hoodin a fixed relationship thereto save for relative rotation about saidaxis of rotation.

Preferably said coupling device is a flexible coupling including a drivechain presenting an input end to engage with said shaft and an outputend to engage with said rotary hub, said input end capable of rotationalaxis misalignment with said output end to allow said hood to swivelrelative to said input end of said drive chain yet still allow in use acontinuous power to be provided by said motor via said shaft to saidrotary shaft.

Preferably said flexible coupling includes a flexible interconnectionstructure fixed at one end relative to said hood and to be fixed at theother end to said sleeve of said prime mover and relative to which saiddrive chain is in use to rotate.

Preferably said flexible interconnection structure is a hollow flexibleelongated interconnecting structure within which said drive chain atleast in part extends.

Preferably said coupling device is a universal joint like coupling.

Preferably said coupling device is a kinematic coupling.

Preferably said coupling device is a CV joint.

Preferably said coupling device is of a mechanical linkage joint.

Preferably said flexible interconnection structure includes a ball andsocket connection.

Preferably said flexible interconnection structure is a bendable sleevethrough which said drive chain extends.

Preferably said coupling device is a coupling region of and at anaxially distal end of said rotary shaft to said cutting means and withwhich said shaft of said prime mover is able to directly engage.

Preferably a fan is mounted from said rotary shaft for rotation relativeto said hood and about said axis of rotation and within the perimeter ofsaid hood in a manner to generate an airflow which in use is in adirection outward from the opening of said hood.

Preferably said cutting means is provided intermediate of said openingand said fan.

Preferably said fan is a centrifugal fan and the airflow generated byits rotation is displaced in a generally radial direction and inconsequence of said hood being substantially enclosing to airflowgenerated travelling away from said opening, said air flow is expelledfrom said hood in a direction outward from cutting chamber via saidopening.

Preferably said fan is an axial fan and the airflow generated byits-rotation is displaced in a generally axial direction to be expelledfrom said hood in a direction outward via said opening.

Preferably said fan includes a plurality of fan blades.

Preferably said fan is mounted from said rotary shaft.

Preferably said hood includes upper enclosure defining surface(s) whichin general slope in a direction towards said opening to provideentrainment surface(s) to said airflow generated by said fan in create aflow direction generally towards said opening.

Preferably wherein rotational speed changing means are providedintermediate of said rotary shaft and said coupling device.

Preferably said rotational speed changing means is a speed changinggear.

Preferably said hood includes a cavity within which a fan is mounteddependent from said rotary hub for rotation about said axis of rotation,said cavity being separate from said cutting chamber save for at leastone opening to direct airflow from said cavity to said cutting chamberand towards the opening of said hood.

Preferably said cutting means includes at least one cutting blade.

Preferably said at least one cutting blade is a metal cutting blade withit said cutting edge presented perpendicular to the axis of rotation.

Preferably said means to cut includes at least one metal cutting bladewith it said cutting edge presented perpendicular to the axis ofrotation and parallel to the plane of said opening, said cutting edgeplaced on the cutting chamber side of said opening.

Preferably said cutting means includes at least one flexible cuttingwire extending from said rotary shaft.

Preferably said cutting means is positioned immediately adjacent theopening to said hood on the cutting chamber side of said opening.

Preferably said hood is extensive over said cutting means from alldirections save from said opening presented direction.

In a second aspect the present invention consists in a lawn trimmer toolcomprising;

-   -   a motor    -   a rotary trimmer unit which derives rotational power from said        motor via an elongate shaft attached to be rotationally driven        by said motor, said shaft captured substantially within a        protective sleeve    -   wherein said rotary trimmer unit comprising,    -   a means to cut    -   a hood extensive over said means to cut yet exposing said means        to cut through a (preferably substantially planar) hood opening        which in use is to be positioned parallel to and juxtaposed the        ground over which the hood is swung by a user    -   a means to couple disposed at the end of said elongate shaft        distal from said motor and being a flexible coupling allowing        said hood to rotate in use about at least one axis substantially        parallel to the ground over which said hood is swung by a user,    -   a means to support said lawn trimmer tool by a user, said means        to support disposed from or provided at the protective sleeve        intermediate of said motor and said rotary trimmer unit.

Preferably said hood is mounted secured to, yet flexibly disposed from,said sleeve to be supported thereby to allow said hood to rotate in useabout said at least one axis.

Preferably said at least one axis includes a second axis transverse tosaid first mentioned axis and parallel to said ground.

Preferably said means to couple is a flexible tendon providing infiniteaxes of rotation of said hood parallel to said ground.

Preferably said means to couple is a flexible tendon providing a freedomof movement of said hood about any parallel to the ground axis ofrotation.

Preferably said means to couple is a flexible tendon and through which aflexible shaft for transmission of rotation is provided.

Preferably said means to couple is a flexible tendon- and through whichsaid shaft is provided for transmission of rotation is provided, saidshaft being flexible in at least that region extending through saidflexible tendon.

Preferably said means to couple is a flexible sleeve.

Preferably a fan is disposed within said hood to rotate with said meansto cut and to generate a draft of air to encourage the hovering of saidhood, in use, above the ground.

Preferably said fan is coaxial with said means to cut.

In a further aspect the present invention consists in a lawn trimmercomprising;

-   -   a motor    -   a rotary trimmer unit which derives rotational power from said        motor via an elongate shaft attached at one end to said motor        and at the other end to said rotary trimmer, said shaft captured        substantially within a protective sleeve    -   wherein said rotary trimmer unit comprising,    -   a means to cut to derive rotation from said motor via-said        elongate shaft,    -   a hood extensive over said means to cut to define a cutting        cavity therein, yet exposing said means to cut through a        (preferably substantially planar) hood opening which in use is        to be positioned parallel to and juxtaposed the ground over        which the hood is swung by a user    -   a fan disposed within said hood defined cutting cavity and        juxtaposed to said cutting means intermediate of said hood and        said cutting means, said fan rotatable by said motor to in use        generate a draft to encourage the hovering of said hood above        the ground,    -   a means to support said lawn trimmer tool by a user, said means        to support disposed from or provided at the protective sleeve        intermediate of said motor and said rotary trimmer unit.

Preferably said fan is co-rotational with said cutting means.

Preferably said fan is coaxial with said cutting means.

Preferably said fan includes a disk shaped region from which and towardsone side thereof there is disposed a plurality of radially extendingblades.

Preferably said cutting means and said fan are mounted from a stub axlemounted from said hood in a manner rotational about a rotational axis inuse normal to the surface of said ground over which said hood is moved.

In still a further aspect the present invention consists in a lawntrimming device attachable or attached to the power take off end of aline trimmer primary unit to be powered by said line trimmer, said tooldevice

-   -   a hood with a downwardly facing opening to allow the opening to        be placed parallel to the ground, said hood defining a cutting        cavity,    -   a means for coupling said hood to said line trimmer primary unit    -   a shaft    -   a cutting means rotatably mounted relative to said hood from        said shaft, said shaft engaged or engageable to the line trimmer        primary unit to derive rotational power from said line trimmer        primary unit, said cutting means positioned within said cutting        cavity of said hood adjacent said opening    -   wherein said hood provides protective cover to said cutting        means save for its exposure at least to said opening, wherein in        use said cutting means can engage with grass exposed to said        cutting means below said hood.

Preferably said hood is pivotally mounted to said line trimmer primaryunit.

Preferably said opening is provided in a location directed away fromsaid primary unit such that in use said primary unit extends upwardlyaway from said hood.

Preferably a fan is mounted within said cutting cavity and is rotatablerelative to said hood and derives rotational power from said linetrimmer primary unit to generate a draft within said cutting cavity toencourage the hovering of said fan, in use, above said ground.

This invention may also be said broadly to consist in the parts,elements and features referred to or indicated in the specification ofthe application, individually or collectively, and any or allcombinations of any two or more of said parts, elements or features, andwhere specific integers are mentioned herein which have knownequivalents in the art to which this invention relates, such knownequivalents are deemed to be incorporated herein as if individually setforth.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view through a lawn trimmer attachment unit of thepresent invention,

FIG. 1 a is a side view of a line trimmer with a lawn trimmer attachmentunit engaged thereto,

FIG. 2 is a sectional view through an attachment wherein an alternativecoupling arrangement is provided,

FIG. 3 is a sectional view through an attachment wherein an alternativecoupling arrangement is provided,

FIG. 4 is a sectional view through an attachment wherein an alternativecoupling arrangement is provided,

FIG. 5 is a sectional view through a fixed lawn mowing unit attached toa line trimmer primary unit,

FIG. 6 illustrates an alternative coupling arrangement to the couplingof FIG. 5,

FIG. 7 illustrates an alternative coupling arrangement to the couplingof FIG. 5,

FIG. 8 illustrates an alternative arrangement to the couplingarrangement of FIG. 5.

FIG. 9 illustrates an alternative arrangement of the fan and the meansto cut,

FIG. 10 is a sectional view through an attachment wherein an alternativearrangement of the hood is provided,

FIG. 11 is a sectional view through a lawn trimmer attachment unit ofanother embodiment of the present invention,

FIG. 12 is a sectional view through a lawn trimmer attachment unit ofanother embodiment of the present invention, and

FIG. 13 is a perspective view of the end of the shaft of the lawntrimmer attachment unit.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1A there is shown a lawn trimmer attachment unit1 which is engaged to a line trimmer primary unit 2. The line trimmerprimary unit 2 for example consists of a motor 3 which may be anelectric motor. Alternatively and certainly preferably it is an internalcombustion engine such as a two or four stroke petrol engine. The motor3 is engaged to a shaft 4 which is driven by the motor 3. The shaft 4 ispreferably enclosed within a protective sleeve 5. At the second distalend 6 opposite to the distal end 7 where the shaft 4 is engaged to themotor, there is provided the lawn trimmer attachment unit 1. In someforms of the present invention the lawn trimmer attachment unit 1 may bepermanently attached to the line trimmer primary unit 2. Alternativelythe lawn trimmer attachment unit 1 may be removeably engaged to the linetrimmer primary unit 2. With reference to FIGS. 1-4, a removableattachment is shown. With reference to FIGS. 5-8, a permanent althoughmechanically removable attachment is provided. With reference to FIG. 1,the lawn trimmer attachment unit 1 is engaged to the shaft at region 10.Such a coupling may be for example by a mechanical coupling such as asplined drive or the like. The lawn trimmer attachment unit 1 includes ahood 11 which provides an enclosure 12 within which a trimmer assembly13 is mounted.

The enclosure 12 (or cutting cavity) includes an opening 14 which whenthe device is in use is bounded by the perimeter 15 of the hood. Theperimeter 15 defines an opening plane which is substantially parallel tothe ground over which the lawn trimmer attachment unit 1 is swung. Thetrimming assembly 13 includes a shaft 16 (or stub axle) which isrotationally dependent from the hood 11. The shaft 16 is rotatable aboutan axis 17 which is substantially normal to the plane of the opening 14defined by the hood. Bearings mount the shaft from the hood.

The shaft 16 is coupled by a coupling 18 to the shaft 4 of the linetrimmer primary unit. The hood may for example be made from a sheetmetal material or from a moulded plastics material. The hood providesprotection to the trimming assembly 13 and to persons standingthereabout and only exposes the trimming assembly to the ground-via theopening 14. The trimming assembly 13 includes blades 19 which are theblades which rotate with the shaft 16 about the axis 17 and subject thegrass which enters into the enclosure 12 via the opening 14 to a cuttingaction. The blades in the examples shown are preferably of a fixed andsolid blade such as for example ones made from a sheet metal material.However alternatively the blades may be defined by nylon or othersynthetic wire strings. The strings will be attached to a hub mountedcentrally about the shaft 16 and from which the nylon will radiallyextend.

In one preferred embodiment of the present invention the hood 11 alsohas captured within its enclosure 12 a fan 20. The fan is also mountedfrom the shaft 16 and rotatable about its axis of rotation. The fan willinclude a plurality of fan blades 21 which are provided to create adowndraft within the enclosure directing air flow in a downwarddirection. Airflow within the enclosure 12 and forced in a downwarddirection will result in a hovering effect provided by the unit as itpasses over the ground. The downdraft will create an elevating effect tothe hood thereby ensuring that the hood can be kept above the groundwith minimal support from the strength of a user holding the linetrimmer. The air will squeeze out between the perimeter 15 of the hoodand the ground. The perimeter 15 of the hood providing a substantiallyplanar opening 14 will allow for the cutting elements 19 to bemaintained at a height no less than the height X between the perimeterand the distance that the cutting elements 19 are positioned within theenclosure 12 from the perimeter 15 of the hood. Accordingly there is aminimum height that is provided as cutting of the grass occurs by thelawn trimmer attachment unit 1 of the present invention. Accordingly theperimeter 15 of the hood provides a height gauge between the ground andthe blades 19 in order to prevent the blades from gauging the grass. Thehood is preferably in plan view of a circular perimeter shape.

In the preferred form, the fan 20, which is mounted from the shaft 16,is driven by the motor 3. In an alternative form, the fan 20 may bedriven by a second motor, independent from the motor 3.

Further, in the preferred form, the fan 20 and the blades 19 are of asingle unit as depicted in FIG. 1. In an alternative form as depicts inFIG. 9, the fan and the blades can be of two separate units, bothmounted from said shaft 16. It is appreciated that both the fan and theblade may be driven by the same motor 3 or be driven by two separatemotors thereby allowing different rotational speeds to be achieved.

In another embodiment when the fan and the blades are of two separateunits or part of the same unit, a second hood may be providedintermediate the fan and the blades such that the fan is disposedintermediate the first and the second hoods as shown in FIG. 10. Outlets61 to the cavity 60 are provided to direct the flow of air.

The primary trimmer unit extends from an upper surface (surface oppositeto the opening) of the hood upwardly in a direction to allow a person tohold the device and sweep the hood over the ground.

A quick attachment mechanism 23 is preferably provided to allow for thelawn trimmer attachment unit 1 as per FIG. 1-4 to be released andquickly attachable to a line trimmer primary unit. Such attachment willpreferably occur by the engagement of the lawn trimming unit to thedistal end 6 of the shaft 4 and sleeve 5 of the primary unit. The quickattachment in FIG. 1 is shown in two positions a first position 23 awherein the unit is engaged and 23 b wherein the quick release allowsfor the unit to become detached from the primary unit. In an alternativeor additional preferred form the hood 11 and the trimming assembly 13are preferably mounted from the line trimmer primary unit in a flexiblemanner. Such a flexible disposition of the hood and trimmer unit 13 fromthe line trimmer primary unit will allow for the hood to follow anyuneven contours in the ground or to allow for the adaption of the hoodrelative to the primary unit in a manner to ensure that the hood ismaintained in a disposition relative to the ground so that the perimeter15 remains parallel therewith. The coupling 18 is accordingly of aflexible coupling type 26 such as for example shown in FIGS. 1-8 savefor FIG. 1A. The flexible coupling 26 will allow for a pivoting of thehood 11 relative to the shaft 4 of the primary unit to allow for desiredrotation to occur. Such rotation is preferably about axes which aresubstantially horizontal. The mounting will allow for the power from themotor to still be delivered to the cutting unit 13 to rotate the cuttingunit 13 about its axis 17. The flexible mounting 26 may be of amechanical type and examples include the constant velocity joint asshown in FIG. 1 or the universal joint as shown in FIGS. 3, 6, 7. Inorder to prevent the hood 11 from rotating about the axis 17 a flexiblemounting 27 is provided which allows for the pivoting of the hoodrelative to the sleeve 5 of the primary unit. A flexible mounting 26 mayfor example be of a rubber or plastics mounting which can deflect. Suchis for example shown in FIGS. 1, 5 and 6. Alternatively a ball andsocket coupling 27 as for example shown in FIGS. 2, 4, 7 and 8 may beused for such purposes. The flexible mounting will allow for the hoodand trimming assembly to gimble relative to the primary unit. Themovement that may be allowed by the flexible connection and the couplingmay be over a radius of 45 degrees (or preferably 20 degrees) eitherside of the vertical and about a horizontal pivot. Many types ofkinematic like flexible couplings can be used.

The present invention herein described allows for rotation of said shaft16 with a single speed. In another embodiment of the present inventionas depicted in FIG. 11, the lawn mower-attachment 1 is provided with agear box extending from the flexible mounting 26 for varying therotational speed of said shaft 16. It is appreciated by a person skilledin the art that gears of various kind, such as gears with the use ofbelts, chains or pulleys may be employed for the said purpose.

The use of gears (or belt's/chain's/pulley's) to give lateral orvertical differential in any plane, e.g. by the use of bevelled gears.

With reference to FIG. 12 there is shown a lawn trimmer attachment unit1 which has a sleeve 53 extending from the motor (not shown) and withinwhich a shaft 50 to allow for the trimming assembly to derive rotationalpower from the motor disposed therein. The shaft 50 may in part or inits entirety be of a flexible nature such that its axis of rotation isnot constant over its entire length. As can be seen with reference toFIG. 12, the shaft 50 curves towards the distal end of the sleeve 53 forits presentation to be substantially vertical at the distal end of theshaft 50. Whilst the sleeve 53 terminates at region 52 the distal end ofthe shaft 54 extends beyond the distal end 52 of the sleeve 53. Indeedthe portion of the shaft 50 extending beyond the distal end of thesleeve 53 becomes located within a flexible tendon or flexible sleeve 55which forms the coupling between the lawn trimmer attachment unit 1 andthe sleeve 53 of the primary line trimming unit. The flexible tendon 55is preferably of a rubber hose or sleeve or similar cylindricalconfiguration but is flexible such that its end engaged to the distalend 52 of the sleeve 53 and the end 56 engaged to a portion of the hood11 can establish non-parallel axial dispositions. The flexible tendonpreferably remains attached with the lawn trimmer attachment unit 1.

As a consequence of such flexibility the hood 11 can move relative tothe distal end 52 of the flexible sleeve 53 and thereby allow the hoodto pivot relative to the sleeve 53 about any number of axes which may begenerally described as horizontal axes (i.e. axes substantially normalto the axis of rotation of the trimming assembly). With reference toFIG. 12, the lawn trimmer attachment unit 1 includes a hub 66 or bearinghouse 66 within which bearings 77 are disposed for the holding of theshaft or stub axle 16 in a fixed location relative to the hood 11. Thehub has-engaged therewith at its end 56, the flexible tendon in arotationally fixed condition at least at its distal end 56. The otherend 59 of the flexible tendon is fixed to the end 52 of the sleeve 53.As a consequence of such fixing minimal or no relative rotation occursbetween the hood 11 and the sleeve 53 other than about the horizontalaxes the rotation about which is provided for by the flexible tendon 55.The flexible tendon 55 is hence sufficiently rigid in a torsional senseto prevent the rotation of the hood 11 and its hub 66 about the axis ofrotation of the trimming assembly during use.

The hood 11 may include air inlet ports 92 which allows for air to bedrawn into the cutting cavity of the hood 11. A dust cover or bellowlike arrangement 46 may be provided to extend to at least enclose theflexible tendon 55 and also the hub 66. In the configuration as forexample shown in FIG. 12 the line trimming attachment unit 1 is of akind permanently attached with the line trimming base unit. However thisconfiguration may be conveniently adopted by the provision of afastening ring or clamp about the first distal end 59 of the flexibletendon to allow it to clamp with the distal end 52 of the sleeve 53.Such a clamp, akin to a hose clamp but operational in a manual mannerpreferably without tooling by a user, can extend about the flexibletendon 55 at its end 59 to clamp with the distal end 52 of the sleeve53. The prior insertion of the distal end 52 within the end opening ofthe flexible tendon 55 and by engaging the end 54 of the flexible shaft50 with the stub axle 16 can allow for a retrofittable and alsoremovable assembly of the lawn trimmer attachment unit 1 with a primaryline trimming unit to be defined. Provided at the distal end 54 of theflexible shaft 50 may be a keyed end section which can insert into acomplimentary shaped key receiving region of the end of the stub axle16. A square drive key or spline like key configuration may be providedfor such purposes. In this manner torque can be transmitted from theflexible shaft 50 to the fan 20 and cutter 19. The square drive can beinserted into a square receiving region to allow for torque to betransmitted when in the assembled configuration. The end of the shaft 16is for example shown in FIG. 13 and illustrates the key receiving region63 within which a square drive key of the end of the flexible shaft 50can engage. Such a sliding engagement can allow for a simpleretrofittable connection to be established.

With reference to FIG. 1 a it can be seen that in the preferred form theelongate shaft of the prime mover is positioned to, in use be held by auser at an inclined angle to the vertical. This allows a user to graspthe sleeve about the shaft and hold the device in a condition to allowit to be swung over the ground. Alternatively the user may grasp handleswhich are disposed from the sleeve in order to support the device foruse. With the combination of the fan and the swivelling hood, the devicebecome convenient to be used in that the weight of the device is in partsupported by the hovering action generated by the fan and need not bemoved in a manner to keep the shaft in the same condition relative tothe surface over which the hood is moved as a result of the flexibilityin the coupling to allow the hood to contour over uneven or sloping oreven flat ground as the device is traversed thereover. The shaft of theprime mover is preferably of a length where the handle or handhold ofthe device is intermediate of the motor and the cutting end. The motorin use normally swings being the person holding the device.

1. A lawn trimmer component for attachment to a hand held prime mover ofa kind which includes a motor (electric or internal combustion) withwhich an elongate drive shaft is connected to be rotationally driven bysaid motor said shaft captured substantially within a protective sleeverigidly connected (directly or indirectly) to said motor, said shaftpresented at an end of said sleeve away from said motor for coupling tosaid lawn trimmer component, said lawn trimmer component comprising: (a)a rotary shaft to derive rotational power via said elongate drive shaftfrom said motor for rotating said rotary shaft about an axis of rotation(b) a coupling device engaged to said rotary shaft and engagable withsaid end of said sleeve of said prime mover (c) a cutting means engagedto and radially disposed from said rotary shaft to rotate about saidaxis of rotation (d) a hood defining a cutting chamber extensive oversaid cutting means yet exposing said cutting means to an opening of saidhood which, in use, is to be positioned juxtaposed the ground over whichsaid lawn trimmer component is, by control of said prime mover, moved bya user, wherein said hood is mounted stationary to said rotary shaftsave for the relative rotation of said rotary shaft with said hood aboutsaid axis of rotation.
 2. A lawn trimmer component as claimed in claim 1wherein said opening of said hood is a planar opening.
 3. A lawn trimmercomponent as claimed in claim 3 wherein said cutting means extends fromsaid rotary shaft to present a cutting edge thereof substantiallyparallel to the plane of said opening.
 4. A lawn trimmer component asclaimed in claim 1 wherein said opening of said hood is at leastcoextensive with the cutting profile generated by said cutting meanswhen rotated about said axis of rotation.
 5. A lawn trimmer component asclaimed in claim 2 wherein said opening of said hood is at leastcoextensive with the circular perimeter traced by said cutting edge whenrotated about said axis of rotation.
 6. A lawn trimmer component asclaimed in claim 1 wherein said rotary shaft is engaged to and to besupported from said hood by a cylindrical bearing.
 7. A lawn trimmercomponent as claimed in claim 1 wherein said rotary shaft includes acutting means mount with which said cutting means is affixed and a stubaxle extending therefrom coaxial with said axis of rotation, said stubaxle supporting said hood in a fixed relationship thereto save forrelative rotation about said axis of rotation.
 8. A lawn trimmercomponent as claimed in claim 1 wherein said coupling device is aflexible coupling including a drive chain presenting an input end toengage with said shaft and an output end to engage with said rotary hub,said input end capable of rotational axis misalignment with said outputend to allow said hood to swivel relative to said input end of saiddrive chain yet still allow in use a continuous power to be provided bysaid motor via said shaft to said rotary shaft.
 9. A lawn trimmercomponent as claimed in claim 8 wherein said flexible coupling includesa flexible interconnection structure fixed at one end relative to saidhood and to be fixed at the other end to said sleeve of said prime moverand relative to which said drive chain is in use to rotate.
 10. A lawntrimmer component as claimed in claim 9 wherein said flexibleinterconnection structure is a hollow flexible elongated interconnectingstructure within which said drive chain at least in part extends.
 11. Alawn trimmer component component as claimed in claim 1 wherein saidcoupling device is a universal joint like coupling.
 12. A lawn trimmercomponent as claimed in claim 1 wherein said coupling device is akinematic coupling.
 13. A lawn trimmer component as claimed in claim 1wherein said coupling device is a CV joint.
 14. A lawn trimmer componentas claimed in claim 1 wherein said coupling device is of a mechanicallinkage joint.
 15. A lawn trimmer component as claimed in claim 9wherein said flexible interconnection structure includes a ball andsocket connection.
 16. A lawn trimmer component as claimed in claim 9wherein said flexible interconnection structure is a bendable sleevethrough which said drive chain extends.
 17. A lawn trimmer component asclaimed in claim 1 wherein said coupling device is a coupling region ofand at an axially distal end of said rotary shaft to said cutting meansand with which said shaft of said prime mover is able to directlyengage.
 18. A lawn trimmer component as claimed in claim 1 wherein a fanis mounted from said rotary shaft for rotation relative to said hood andabout said axis of rotation and within the perimeter of said hood in amanner to generate an airflow which in use is in a direction outwardfrom the opening of said hood.
 19. A lawn trimmer component as claimedin claim 18 wherein said cutting means is provided intermediate of saidopening and said fan.
 20. A lawn trimmer component as claimed in claim18 wherein said fan is a centrifugal fan and the airflow generated byits rotation is displaced in a generally radial direction and inconsequence of said hood being substantially enclosing to airflowgenerated travelling away from said opening, said air flow is expelledfrom said hood in a direction outward from cutting chamber via saidopening.
 21. A lawn trimmer component as claimed in claim 18 whereinsaid fan is an axial fan and the airflow generated by its rotation isdisplaced in a generally axial direction to be expelled from said hoodin a direction outward via said opening
 22. A lawn trimmer component asclaimed in claim 18 wherein said fan includes a plurality of fan blades.23. A lawn trimmer component as claimed in claim 18 wherein said fan ismounted from said rotary-shaft.
 24. A lawn trimmer component as claimedin claim 18 wherein said hood includes upper enclosure definingsurface(s) which in general slope in a direction towards said opening toprovide entrainment surface(s) to said airflow generated by said fan increate a flow direction generally towards said opening.
 25. A lawntrimmer component as claimed in claim 1 wherein rotational speedchanging means are provided intermediate of said rotary shaft and saidcoupling device.
 26. A lawn trimmer component as claimed in claim 25wherein said rotational speed changing means is a speed changing gear.27. A lawn trimmer component as claimed in claim 1 wherein said hoodincludes a cavity within which a fan is mounted dependent from saidrotary hub for rotation about said axis of rotation, said cavity beingseparate from said cutting chamber save for at least one opening todirect airflow from said cavity to said cutting chamber and towards theopening of said hood.
 28. A lawn trimmer component as claimed in claim 1wherein said cutting means includes at least one cutting blade.
 29. Alawn trimmer component as claimed in claim 28 wherein said at least onecutting blade is a metal cutting blade with it said cutting edgepresented perpendicular to the axis of rotation.
 30. A lawn trimmercomponent as claimed in claim 2 wherein said means- to cut includes atleast one metal cutting blade with it said cutting edge presentedperpendicular to the axis of rotation and parallel to the plane of saidopening, said cutting edge placed on the cutting chamber side of saidopening.
 31. A lawn trimmer component as claimed in claim 1 wherein saidcutting means includes at least one flexible cutting wire extending fromsaid rotary shaft.
 32. A lawn trimmer component as claimed in claim 1wherein said cutting means is positioned immediately adjacent theopening to said hood on the cutting chamber side of said opening.
 33. Alawn trimmer component as claimed in claim 1 wherein said hood isextensive over said cutting means from all directions save from saidopening presented direction.
 34. A lawn trimmer tool comprising; a motora rotary trimmer unit which derives rotational power from said motor viaan elongate shaft attached to be rotationally driven by said motor, saidshaft captured substantially within a protective sleeve wherein saidrotary trimmer unit comprising, a means to cut a hood extensive oversaid means to cut yet exposing said means to cut through a (preferablysubstantially planar) hood opening which in use is to be positionedparallel to and juxtaposed the ground over which the hood is swung by auser a means to couple disposed at the end of said elongate shaft distalfrom said motor and being a flexible coupling allowing said hood torotate in use about at least one axis substantially parallel to theground over which said hood is swung by a user, a means to support saidlawn trimmer tool by a user, said means to support disposed from orprovided at the protective sleeve intermediate of said motor and saidrotary trimmer unit.
 35. A lawn trimmer as claimed in claim 34 whereinsaid hood is mounted secured to, yet flexibly disposed from, said sleeveto be supported thereby to allow said hood to rotate in use about saidat least one axis.
 36. A lawn trimmer as claimed in claim 34 whereinsaid at least one axis includes a second axis transverse to said firstmentioned axis and parallel to said ground.
 37. A lawn trimmer asclaimed in claim 34 wherein said means to couple is a flexible tendonproviding infinite axes of rotation of said hood parallel to saidground.
 38. A lawn trimmer as claimed in claim 34 wherein said means tocouple is a flexible tendon providing a freedom of movement of said hoodabout any parallel to the ground axis of rotation.
 39. A lawn trimmer asclaimed in claim 34 wherein said means to couple is a flexible tendonand through which a flexible shaft for transmission of rotation isprovided.
 40. A lawn trimmer as claimed in claim 34 wherein said meansto couple is a flexible tendon and through which said shaft is providedfor transmission of rotation is provided, said shaft being flexible inat least that region extending through said flexible tendon.
 41. A lawntrimmer as claimed in claim 34 wherein said means to couple is aflexible sleeve.
 42. A lawn trimmer as claimed in claim 34 wherein a fanis disposed within said hood to rotate with said means to cut and togenerate a draft of air to encourage the hovering of said hood, in use,above the ground.
 43. A lawn trimmer as claimed in claim 42 wherein saidfan is coaxial with said means to cut.
 44. A lawn trimmer comprising; amotor a rotary trimmer unit which derives rotational power from saidmotor via an elongate shaft attached at one end to said motor and at theother end to said rotary trimmer, said shaft captured substantiallywithin a protective sleeve wherein said rotary trimmer unit comprising,a means to cut to derive rotation from said motor via said elongateshaft, a hood extensive over said means to cut to define a cuttingcavity therein, yet exposing said means to cut through a (preferablysubstantially planar) hood opening which in use is to be positionedparallel to and juxtaposed the ground over which the hood is swung by auser a fan disposed within said hood defined cutting cavity andjuxtaposed to said cutting means intermediate of said hood and saidcutting means, said fan rotatable by said motor to in use generate adraft to encourage the hovering of said hood above the ground, a meansto support said lawn trimmer by a user, said means to support disposedfrom or provided at the protective sleeve intermediate of said motor andsaid rotary trimmer unit.
 45. A lawn trimmer as claimed in claim 44wherein said fan is co-rotational with said cutting means.
 46. A lawntrimmer as claimed in claim 44 wherein said fan is coaxial with saidcutting means.
 47. A lawn trimmer as claimed in claim 44 wherein saidfan includes a disk shaped region from which and towards one sidethereof there is disposed a plurality of radially extending blades. 48.A lawn trimmer as claimed in claim 44 wherein said cutting means andsaid fan are mounted from a stub axle mounted from said hood in a mannerrotational about a rotational axis in use normal to the surface of saidground over which said hood is moved.
 49. A lawn trimming deviceattachable or attached to the power take off end of a line trimmerprimary unit to be powered by said line trimmer, said device including:a hood with a downwardly facing opening to allow the opening to beplaced parallel to the ground, said hood defining a cutting cavity, ameans for coupling said hood to said line trimmer primary unit a shaft acutting means rotatably mounted relative to said hood from said shaft,said shaft engaged or engageable to the line trimmer primary unit toderive rotational power from said line trimmer primary unit, saidcutting means positioned within said cutting cavity of said hoodadjacent said opening wherein said hood provides protective cover tosaid cutting means save for its exposure at least to said opening,wherein in use said cutting means can engage with grass exposed to saidcutting means below said hood.
 50. A lawn trimming device as claimed inclaim 49 wherein said hood is pivotally mounted to said line trimmerprimary unit.
 51. A lawn trimming device as claimed in claim 49 whereinsaid opening is provided in a location directed away from said primaryunit such that in use said primary unit extends upwardly away from saidhood.
 52. A lawn trimming device as claimed in claim 49 wherein a fan ismounted within said cutting cavity and is rotatable relative to saidhood and derives rotational power from said line trimmer primary unit togenerate a draft within said cutting cavity to encourage the hovering ofsaid fan, in use, above said ground.